1. Field of the Invention
The invention relates to an elongate structure curvature sensing device.
2. Description of Related Art
Current pipe survey methods included position measurement using remotely operated vehicles (ROV) or autonomous underwater vehicles with acoustic positioning technology based on the time of flight of sound pulsed through water. Other methods include side-scan sonar from an ROV or a vessel. All of these techniques obtain a measurement of the pipe position at a number of locations. When deriving bending stress from the position information, the high level of noise on the position measurement equates to a very high level of noise on the derived bending measurement and it is widely known that position measurement can not be used to provide accurate measurements of bending in installed pipelines.
Other techniques to measure the stresses in installed pipelines include intelligent pigs, devices with measurement capability that are sent along the inside of the pipeline. Pigs with instruments to measure acceleration have been used to try an measure bending stresses and shapes of pipelines, but again processing acceleration measurements to obtain bending stresses generates significant errors.